[significant_drop_tightening] Add MVP

[c410-f3r]

cc #9399

Creates the lint with minimum functionalities, which is a good start IMO.

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changelog: new lint: [significant_drop_tightening]
#10163

[rustbot]

r? @llogiq

(rustbot has picked a reviewer for you, use r? to override)

[llogiq]

Feel free to add the tests and implementation. Then I'll try and have a review within the next 7 days or possibly sooner, so we don't need to carry incomplete code through.

[c410-f3r]

@llogiq If you have the bandwidth to review a full PR, then I will reach back to you in the following weeks with a more mature implementation.

[llogiq]

@rustbot author

[c410-f3r]

@llogiq The lint is now in a minimal functional state for experimentation in the sense that it will detect and suggest some situations were a path/bind/variable marked with #[clippy::has_significant_drop] is being dropped at the end of its encapsulated block.

Pretty much as arithmetic_side_effects; rough edges, bugs and enhancements will be figured out in a sequence of future subsequent PRs.

[c410-f3r]

cargo dev fmt is locally panicking 🤷

Formatting check failed.
Run `cargo dev fmt` to update formatting.

[c410-f3r]

@rustbot label -S-waiting-on-author +S-waiting-on-review

[llogiq]

Thank you! In general, this looks good. It certainly meets our standards for a nursery lint. I have but a few niggles on code style, please address them, and then I'll gladly r+.

[llogiq]

One final nit, then I'll be happy to have bors merge this.

[llogiq]

Thank you!

@bors r+

[bors]

📌 Commit 1b286b1 has been approved by llogiq

It is now in the queue for this repository.

[bors]

⌛ Testing commit 1b286b1 with merge 4369a67...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: llogiq
Pushing 4369a67 to master...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: llogiq
Pushing 4369a67 to master...

[c410-f3r]

Thanks @llogiq